APPARATUS AND METHOD FOR THERMAL PROFILE CONTROL IN AN ISOPIPE

• US 20140318182A1
• Filed: 01/31/2014
• Published: 10/30/2014
• Est. Priority Date: 04/30/2013
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Coppola, Frank, Golyatin, Vladislav Yuryevich, Kersting, John Jerry, Kocatulum, Bulent, Mashewske, Monica Jo, Wesolowski, Piotr Janusz, Xie, Xi
• Granted Patent: US 9,914,657 B2
• Time in Patent Office: Days
• US Class Current: 65/29.21
• CPC Class Codes: C03B 17/02 Forming molten glass coated with coloured layers; Forming molten glass of different compositions or layers; Forming molten glass comprising reinforcements or inserts
• CPC Class Codes: C03B 17/064 by the overflow downdraw fusion process; Isopipes therefor
• CPC Class Codes: C03B 17/067 combined with thermal conditioning of the sheets

Abstract

A glass fusion draw apparatus for molten glass stream thermal profile control, including:

• • a first enclosure; and
  • a first isopipe situated within the first enclosure,
    the first enclosure can include at least one first heating element assembly integral with the wall of the first enclosure, and the at least one first heating element is in proximity to a portion of molten glass stream over-flowing the first isopipe within the enclosure. The apparatus can also include a proximity or temperature sensing system associated with the first enclosure that senses and controls the thermal gradient properties of the molten glass stream or streams in the first enclosure. Also disclosed are methods of making and using the fusion apparatus.

Claims

1. A glass fusion apparatus for molten glass stream thermal profile control, comprising:

a first enclosure; and

a first isopipe situated within the first enclosure,

the first enclosure includes a plurality of first heating element assemblies integral with the wall of the first enclosure, and at least one first heating element assembly is in proximity to a portion of molten glass stream over-flowing the first isopipe within the enclosure.

2. The apparatus of claim 1 wherein the plurality of first heating element assemblies integral with the wall of the first enclosure are fitted into slots on the exterior of the enclosure and are connected to a source of electricity.

3. The apparatus of claim 1 wherein each of the first heating element assemblies comprises at least one wire winding support having a plurality of vias and having a plurality of resistive wires interleaved on the plurality of vias of the support.

4. The apparatus of claim 1 wherein the first heating element assemblies comprise at least one of:

at least one wire winding support situated on each of two opposing sides of the first enclosure;

at least one wire winding support situated directly opposite on two opposing sides of the first enclosure; and

a plurality of wire winding supports situated on the same side of the first enclosure at a first elevation and a plurality of wire winding supports situated on the opposite side of the first enclosure at the first elevation.

5. The apparatus of claim 1 wherein the first heating element assemblies comprise a plurality of wire winding supports situated on the same side of the first enclosure and a plurality of wire winding supports situated on the opposite side of the first enclosure, and the plurality of wire winding supports are situated at a first elevation on the enclosure;

at a second elevation on the enclosure;

at a third elevation on the enclosure, or a combination of two or more of the elevations.

6. The apparatus of claim 1 further comprising a second enclosure, the second enclosure encloses at least a portion of the first enclosure;

and a second isopipe situated above and vertically aligned with the first isopipe within the first enclosure.

7. The apparatus of claim 1 further comprising at least one globar heating element situated around the exterior of the enclosure.

9. A method of using the apparatus of claim 1 comprising:

heating the apparatus to thermal equilibrium with the plurality of first heating element assemblies;

charging the apparatus with molten glass from a glass source and forming at least one glass stream flow into a glass ribbon; and

monitoring at least one of;

the temperature profile of the molten glass stream;

the power level profile to the individual or to the collective plurality of first heating element assemblies to maintain the apparatus in thermal equilibrium;

the thickness profile of the glass ribbon controllably formed in the apparatus, or a combination thereof.

10. The method of claim 9 further comprising maintaining at least one of:

the temperature profile of the molten glass stream;

the power level to the plurality of first heating element assemblies to maintain the apparatus in thermal equilibrium;

the thickness of the glass ribbon formed in the apparatus, or a combination thereof.

16. The method of claim 15 wherein the resulting laminate glass article drawn under isothermal conditions in the apparatus of claim 1 has:

a clad layer thickness of from 5 to 300 micrometers, and a thickness variation of about plus or minus 2% or about plus or minus 1 to 2 micrometers, and

a core layer thickness of from 50 to 2,700 micrometers, and a thickness variation of about plus or minus 2% or about plus or minus 1 to 2 micrometers.

8. A laminate fusion apparatus for thermal profile control of a molten glass stream, comprising:

a first enclosure;

a second enclosure encompassing at least a portion of the first enclosure; and

a first isopipe and a second isopipe situated within the first enclosure,

the first enclosure includes a plurality of heating element assemblies integral with the exterior wall of the first enclosure, the heating element assemblies comprise a plurality of wire winding supports having vias, the vias having resistive wire windings, the wire windings being configured to controllably receive energy from an electrical source and dissipate heat into the first enclosure.

11. A laminate fusion draw apparatus, comprising:

a heated tiltable enclosure surrounding at least a portion of an upper isopipe, a lower isopipe, or both isopipes;

a fixed muffle enclosure surrounding at least a portion of the heated tiltable enclosure; and

a non-contact temperature sensing system for determining, and either adjusting or maintaining at least one temperature gradient of the heated tiltable enclosure.

12. The apparatus of claim 11 wherein the non-contact temperature sensing system comprises:

an n×

3 sensor array, where n is from 1 to 40;

a multiplexer and a digital acquisition unit that receives and processes at least one signal from the sensor array; and

a programmable controller that that receives and processes at least one signal from the multiplexer and a digital acquisition unit, and where if the system determines a non-isothermal condition, then the programmable controller generates a temperature adjustment signal, and transmits the signal to a heater of the heated tiltable enclosure to approximate an isothermal temperature profile of the glass in the vicinity of the clad isopipe.

13. The apparatus of claim 12 further comprising a server including a database and data analysis module.

14. The apparatus of claim 11 wherein the non-contact temperature sensing system has an accuracy of plus or minus 0.25% or about plus or minus 2.5°

C. at 1,200°

C.

15. A method of manufacturing a laminated glass article, comprising:

forming a laminated glass article in a fusion draw apparatus, the apparatus comprising;

a heated tiltable enclosure surrounding an upper isopipe and a lower isopipe;

a fixed muffle enclosure surrounding at least a portion of the tiltable enclosure; and

a non-contact temperature sensing system for determining, and adjusting or maintaining at least one temperature gradient of the heated tiltable enclosure while the apparatus is in use drawing and laminating glass;

determining the at least one temperature gradient; and

if the at least one temperature gradient is not isothermal then adjusting the at least one temperature gradient of the tiltable enclosure, or

if the at least one temperature gradient is isothermal then maintaining the at least one temperature gradient of the tiltable enclosure as isothermal.

17. The method of claim 15 wherein the laminated glass article comprises at least one borosilicate.

18. The method of claim 15 wherein if the temperature of the tiltable enclosure is maintained at or near an isothermal condition then the resulting laminate glass article has a clad layer and a core layer each having a uniform thickness.

19. The method of claim 15 wherein the resulting laminate glass article drawn under isothermal conditions is substantially free of warp, is a substrate suitable for use in a thin film transistor (TFT) device, or both.